ventilation for energy management and infection prevention

Andrew Streifel Hospital Environment Specialist

University of Minnesota Medical Center

• 38 years service at U of Minnesota infection prevention. • Visited over 400 hospitals & assisted in IAQ infection issues. • Technical expert for ASHRAE, CDC, FGI & other organizations. • Goal to provide evidence based training for prevention of infections during construction & maintenance practice.

Ventilation for Energy Management and Infection Prevention

Why is energy important to infectious disease management?

• Mermazadeh and Xu 2012 recommend site specific risk analysis because increasing or decreasing the room air exchange rate by as little as one air change per hour can result in a differene of $150-250 per year in heating and cooling costs for that room.

Dr. Mermazadeh is the Director of Technical Services NIH.

Levels of Risk Healthy person • Chronic obstructive pulmonary disease • Diabetes • Steroids • Cancer - solid tumor • HIV infection-end stage of spectrum • Organ transplant

– Kidney/heart – Lung/liver

• Malignancy - leukemia/lymphoma Bone marrow transplant (BMT) allograft

Incidence of Healthcare Associated Infections (HAI), U.S. 2011-2012

Annual morbidity: 721,800 – Decrease from 1.7 million estimated in 2002 (NEJM, 2014)

• 1 in every 25 inpatients has at least 1 HAI • Most common: Pneumonia and surgical site infection • Most frequent organism: Clostridium difficile

Annual mortality: 100,000 estimated in 2002 (Klevens, Public Health Reports, 2002) Direct costs associated with HAI: $28.4-$45 Billion (Scott, CDC Paper, 2012) Incidence associated with construction unknown; multiple outbreak papers published

Factors Involved in the Spread of Infectious Diseases

• Droplet nuclei transmission dynamics • Nature of dust levels • Health & condition of individual’s naso-

pharyngeal mucosal lining • Population density in a particular location • Ventilation of the location

Standard Precautions Against Disease Transmission

• Early identification of microbes • Development of appropriate SOPs • Use of PPE including:

– Masks & gloves – Disinfection strategies – Vaccination – Appropriate ventilation design

Indoor Air Quality

Fungi Bacteria Viruses Numerous reports in HCF

Aspergillus spp. Mucorales

M. Tuberculosis Measles virus Varicella-zoster virus

Atypical, occasional reports

Acremonium spp. Fusarium spp Pseudoallescheria boydii Scedosprorium spp. Sporothrix cyanescens

Acinetobacter spp. Bacillus spp. Brucella spp. Staphylococcus aureus Group A. Streptococcus

Smallpox virus Influenza viruses Respiratory syncytial virus Adenoviruses Norwalk-like virus

Airborne in nature; airborne transmission in HCF not described

Coccidioides immitis Cryptococcus spp. Histoplasma capsulatum

Coxiella burnetti (Q fever)

Hantaviruses Lassa virus Marburg virus Ebola virus Crimean-Congo Virus

Organisms Associated with Airborne Transmission

CDC Guideline for Environmental Infection Control Guidelines 2003

Reported Causative Pathogens, According to Type of Infection.

Magill SS et al. N Engl J Med 2014;370:1198-1208.

ASPERGILLUS

Aspergillus fumigatus • prolific spore production

Aerodynamic spore 2-4µm diameter

Recent examples of the frequency of invasive aspergillosis

Underlying condition Incidence Reference/year Acute myeloid leukaemia 8% Cornet, 2002 Acute lymphatic leukaemia 6.3% Cornet, 2002 Allogeneic HSCT 11-15% Grow, 2002;

Marr, 2002

Lung transplantation 6.2-12.8% Minari, 2002; Singh,2003

Heart-lung transplantation 11% Duchini, 2002 Small bowel tranplantation 11% Duchini, 2002 AIDS 2.9% Libanore, 2002

How far can Airborne Viruses Travel?

1. Coughing 1-5 feet 160+ feet 2. Sneezing 8-15 feet 160+ feet 3. Singing, Talking 1-3 feet 160+ feet 4. Mouth Breathing 1-3 feet 160+ feet 5. *Diarrhea 5 feet+ 160+ feet

*As a Result of Toilet Water Aerosolization and Mechanical Fan Dispersion into outdoor air (2003 Hong Kong SARS Virus Epidemic)

Large/Small Droplets Droplet Nuclei

1. Mucus/water encased by the infector or by toilet water. These quickly fall to the ground after traveling up to 1-3 feet.

Stages of Infectious Droplets & Droplet Nuclei

2. Mucus/water coating starts to evaporate. These will travel 3-5 feet before falling to the ground. These droplets can become droplet nuclei.

3. Mucus/water coating has totally evaporated coating the viron particles. These are Droplet Nuclei which are so microscopic they can float in the air.

Diameter of Droplet (µm)

Evaporation time (sec)

Distance fallen in ft. (before evaporation)

200 5.2 21.7

100 1.3 1.4

50 0.31 0.085

25 0.08 0.0053

Evaporation Time & Falling Distance of Droplets Based on Size

Adapted from: Wells, W.F., 1955, Airborne contagion and air Hygiene, Harvard University Press, Cambridge, Mass.

*particles discharged at 6 ft. > 140µm tend to fall to the ground

*particles discharged at 6 ft. < 140µm evaporate to droplet nuclei

Infectious Droplets & Droplet Nuclei travel lengths

Airborne Transmission depends on people to launch viruses

into the air.

People can shed this many Flu Viruses into the air as tissue culture infecting doses (TID)

1. Coughing 3,000+ TID 2. Sneezing 3,000+ TID 3. Breathing: Nose-None Mouth-Varies 4. Talking/Singing 1,000+ TID 5. Vomiting 1,000+ TID 6. *Diarrhea 20,000+ TID

* As a result of Toilet Water Aerosolization

Droplet Nuclei Travel Within Buildings

In hospitals re-circulated air is filtered > 90%

Infectious Droplet Nuclei Recirculation in Buildings

Unusual circumstance demonstrated in Hong Kong hotel and SARS outbreak 2003.

● Viruses Evaporate faster in Low Humidity levels thus creating More Droplet Nuclei. ● Low humidity allows droplet nuclei to stay airborne longer as the droplets do not absorb water weight which would cause them to fall to the ground. ● Indoor Air currents both created by HVAC systems and people movement assure that droplet nuclei will remain airborne Indefinitely. ● This allows HVAC systems to remove and redistribute droplet nuclei throughout the building to infect more occupants.

Low Indoor Humidity Increases Droplet Nuclei Levels (winter)

1) Indoor humidity levels (winter) in the Northern Hemisphere especially in North America and Europe are between 15-35%. 2) Studies have proven that there is no “flu season” in the tropics where indoor humidity levels stay above 40% all year long.

There is a DIRECT correlation between low indoor humidity in

winter and increases in influenza morbidity and mortality

ASHRAE Standard 55-1992 recommends: Relative Humidity between 20% and 60%

Less than 50% RH for dust mite control

Facility Guidelines Institute Design Parameters of Selected Areas Function of Space Relative Humidity % Design Temperature °F/°C Classes B & C Operating Rooms 20-60 68-75/20-24 Burn unit 40-60 70-75/21-24 Newborn intensive care 20-60 70-75/21-24 Patient room(s) max 60 70-75/21-24 Protective environment room max 60 70-75/21-24 Airborne Isolation anteroom N/R N/R ASHRAE STD 170 HEALTHCARE VENTILATION 20% RH CHANGE

Type of Virus Duration of Persistence (range)

Adenovirus 7 days - 3 months

Coxsackie virus > 2 weeks

HBV > 1 week

HIV > 7 days

Respiratory syncytial virus up to 6 hours

Rhinovirus 2 hours - 7 days

Rotavirus 6 - 60 days

Persistence of Clinically Relevant Viruses on Dry Inanimate Surfaces

monitor

corridor

Negative Pressure Room for Airborne Infection Isolation

Bathroom

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Monitorr

Corridor

Bathroom

Positive Pressure Room for Protective Environment

AIA & ASHRAE DESIGN GUIDELINES FOR VENTILATION

CDC EIC MMWR JUNE 6, 2003

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The ICRA Process should Identify Infection Control Risk

Identifies Risk and Mitigation Strategies in Design, Construction and Validation

HOW DO WE BUILD FOR ENERGY MANAGEMENT WHILE MAINTAINING INFECTION PREVENTION GOALS?

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Ventilation: Redundancy

PROPOSED ENERGY EFFICIENCIES Displacement Chill beams Heat wheels Minimal leakage

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Condensation Prevention Exterior Testing Water proof Air infiltration Condensation Cooling Heating Structural

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Condensation Prevention Dynamic Testing

Use pipe grid system to spray water

Use a propeller engine to simulate wind conditions

At 12 PSF for 15 minutes Check for leaks

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Thermal Testing by Cooling

Thermal Testing by Heating

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Condensation Prevention

Thermal Modeling – before installation.

Design conditions: Exterior temp = - 20F Interior Temp = 72F Exterior Wind = 15 mph Interior RH = 30% Dewpoint = 39 F

Cold Snap Sequence of Operation

Thermal Imaging – after installation Minnesota design for extreme

conditions.

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Curtain Wall Testing Detail at

demising walls and slab edge This detail

demonstrated air leakage side to side rooms

Benefits of Active Beams in Healthcare Reduction in air handling equipment Minimization and elimination of ductwork Reduction in reheat Quiet operation Improved indoor air quality Reduced risk of cross contamination

Planning for New Ambulatory Care Center University of Minnesotan Medical Center 2014

Chill beam advantage is to separate the cooling component with the air supply to save energy.

•Must have access for cleaning •Must not condense on the surfaces of the chill beam •A sealed curtain wall helps keep humidity out of the building

Short circuiting airflow

Mixing ventilation

Normal Room Ventilation Conditions

What is displacement ventilation?

Piston airflow

Displacement like piston airflow moves air in single direction that displaces air as it moves The intent being not to mix the air but pushes is it.

The advantages of Displacement ventilation

Energy saving and moving air out of the breathing zone

Studies have shown energy saving by delivering 61 F air instead of 55 F air to the room supply diffusers. Warmer air does not need to be forced down and fall to the Patient. It is warmer and still rises and when above breathing zone clears the air.

Waiting rooms and atriums are very good applications for using this kind of air delivery. DV is also common in auditoriums

Unique diffusor design allows them to be Incorporated into building structure at lower Elevations in respective rooms.

Advantage of Displacement Ventilation for Infection Prevention and Energy Management

Infection Prevention -Room temps may seem warmer due to delivery temp higher. -Rising temp creates upward buoyance to lift particles -When infectious particle above breathing zone safe?

Energy Management -Air delivered to room for comfort already >60F -Lower energy costs -Decrease air exchange for room by using 6 ft instead of 8 ft for calculation

Disadvantage: Difficult to find space in a patient room to deliver air low

Heat Wheels can Reclaim Energy

Aware of air flow direction (clean to dirty) and need to clean the wheel

HVAC – Chilled Water System

AIR WATER REFRIGERANT AIR WATER

75° 54° 105° 88° WB/DB

95°

55° 44° 34° 100° DB 78° WB 85°

Air

Han

dlin

g

Compressor

Chiller

Evaporator Condenser

X

Transfer heat to chiller

PROCESS STEP 1 Transfer heat to atmosphere

PROCESS STEP 2

MEASURE & VALIDATE IMPACT

Systematic Approach to HVAC Systems HVAC is integral to the entire cooling system …

Causes of Ventilation Deficiencies Plugged Filters Plugged Temperature Control Coils Duct Leakage Dust on Fan Blades Fan Belt Slippage Uncalibrated Control Equipment Digital Controls Pneumatic Controls Plugged sensors

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Punching the tubes and cleaning heat exchanger allows efficient energy transfer

Biological Growth Dirty Coils

HVAC Problems

IAQ/Odor: Risks to Distribute, Particles, Odors, Bacteria and Molds Through the Entire Facility

Impact of Air Flow On Room Particle Contamination

Deep Cleaning Process Recover Coil Heat Transfer Performance

Result: More air and

cooler air

Dirty pre filters and final filters

DIRTY CLEAN

Air Safety – Foundational IP Solutions Clinical evidence

• Clostridium difficile is a spore forming enteric bacterial

pathogen and is listed as a Class 1 airborne pathogen (1)

• Influenza, measles, mumps, tuberculosis are infections for which airborne transmission has been documented (2)

• Particles remain airborne for some period of time and HVAC system operation affects the concentration (2)

• The addition of highly efficient filtration to central HVAC systems is likely to reduce the airborne load of infections particles (2)

1. Kowalski, W. (2012), Hospital Airborne Infection Control, CRC Press 2. Airborne Infectious Diseases, ASHRAE Position Document, June 2009

Filter Engineering Solutions Impact of Innovative Filter Technologies

glass fibers

synthetic fibers

Face Loading

Depth Loading

MAINTAIN

Synthetic electro static fibers may degrade quickly

Biological particles seem to be preferentially removed by filters.

While the filter bank of bag filters looks good?

You might not be able to see it all….. When filters oscillate they wear & tear.

Reality Check!

Removal Efficiency In-Situ by Particle Size and Resistance to Flow

Direction of Airflow

Particle Counter

Before After

Before filter 12176 p/ft^3

After filter 40 p/ft^3 >99% reduction

Room 206

Door

Patient Mock-up Room Leakage Application Overview

Why should we seal rooms anyway??

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Ventilation: Patient Room Mock Up Testing

Blower doors allow for leakage testing by applying pressure and using smoke stick to find leaks for sealing

Duct Blaster evaluation of AII room

Depressurize room and record air flow volume to determine room leakage. Four AII rooms evaluated with average of 22 inch2/100ft2; two sealed rooms 3.1 in2/100ft2.

AIR TIGHT HOUSES STANDARD AT 2.5 inch2 /100ft2

Leakage defined as # cfm @ x pressure Pascal’s or WC

Finding leakage points in rooms helps assure consistent pressure management

Design for airborne infection isolation rooms the size at UMMC when sealed will move 84 cfm air at 10 Pascal’s pressure to achieve 2.5 in2/100ft2 surface area. Leakage at about 0.1 cfm/ft^2.

A sealed room has two advantages: -controlled sound movement -ventilation control for infectious disease management

Room Seal Necessary for Special Ventilation Management

• Cracks can result in room air leakage. • Supply air volume differential allows for airflow direction control. • Low pressure differential can result in airflow reversal. • Substantial room pressure design should provide a sealed “vessel”. • Design criteria are necessary for control.

Case Study- Barrier Management “Leakage”

Total Barrier Management

Infection control

Sound

Energy/ Movement

UL systems

Total Barrier Management practices increase build integrity beyond UL systems with additional secondary attributes

DISCLOSURE HILTI SPONSORED STUDY

Staff/Housekeeping/Clean equipment in-flow

Patient in-flow

Patient/Staff/Housekeeping/Dirty Equipment out-flow

HLIU FLOW

Dirty Decon

Dirty Decon

Dirty Ante

Dirty Ante

Clean Ante

Clean Ante Dirty

Ante Dirty Ante

PROPOSED AIR PRESSURE

-5pa -5pa

-7.5pa -7.5pa

-7.5pa -7.5pa

-10pa -10pa

-2.5pa -2.5pa -2.5pa -2.5pa

-5pa -5pa

Interlocking doors

Staff/Housekeeping/Clean equipment in-flow

Patient in-flow

Patient/Staff/Housekeeping/Dirty Equipment out-flow

*Loss of corridor space and 2 x Nurse Alcoves

MOCK UP ROOM CREATED TO TEST WALL PENETRATIONS WITH A BLOWER DOOR

Wall Penetrations Can Circumvent Ventilation Parameters

Plugging holes will help maintain pressure goals

TESTING PENETRATIONS WITH BLOWER DOOR PRESSURIZATION

Application Test Series – Complete Overview

0500

10001500200025003000350040004500500055006000650070007500

Open Sealed Open Sealed Open Sealed Open Sealed Open Sealed Open Sealed

ToW ToW BoW BoW Plumbing Plumbing Low Voltage Low Voltage ElectricalBoxes

ElectricalBoxes

Mechanical * Mechanical

CFM

at 5

0 Pa

scal

Medical Mock-up RoomApplication Test Series Overview

CFM Per Application

Baseline: 180 CFM at 50 Pascal

Source: Testing implemented by The Energy Conservatory. Testing completed w/ Duct Blaster fan and micromanometer measuring flows from 10 to 1500 CFM.

Blower Test # Test Application Status CFM Per Application 1 ToW Open 7000 2 ToW Sealed 98.85 3 BoW Open 98.85 3 BoW Sealed 40.63 4 Plumbing Open 816.3 5 Plumbing Sealed 41.3 6 Low Voltage Open 191.8 7 Low Voltage Sealed 45.96 8 Electrical Boxes Open 135.6 9 Electrical Boxes Sealed 46.52 10 Mechanical * Open 135.6 11 Mechanical Sealed 46.59

Case Study- Barrier Management

Total Barrier

Management

Infection control

Sound

Energy/ Movement

UL systems

Total Barrier Management practices increase build integrity with life Safety and fire secondary attributes

The most common requirement for control is the UL

or life safety considerations as they pertain to fire and smoke control. Hospital corridors and other potential fire hazard need to be sealed Fire management in healthcare has provided safety

to millions of healthcare building occupants resulting in enormous strides in

fire management through regulation. NFPA, Life safety 99 and 101. What additional benefits can be realized?

LIFE SAFETY/FIRE

Case Study- Barrier Management

Total Barrier

Management

Infection control

Sound

Energy/ Movement

UL systems

Total Barrier Management practices increase build integrity and sound migration secondary attributes

Additional benefits of a sealed room include sound

mitigation. It is common acoustical knowledge that sound transmission can be partially mitigated by impeding air movement. This practice occurs where airport noise is managed with sealed houses to minimize

sound wave infiltration. HIPPA requires privacy from hearing patient conditions. Explain some of the physics of sound transmission

SOUND MITIGATION

Case Study- Barrier Management

Total Barrier

Management

Infection control

Sound

Energy/ Movement

UL systems

Total Barrier Management practices increase build integrity and energy & comfort secondary attributes

Building design in healthcare includes inoperable

windows to prevent infiltration of uncontrolled air. Comfort factors are essential to convalescence therefor to maintain

temperature between 68 and 72 can be difficult without controlled ventilation. Leakage reduction will require less heating and

cooling?? Does a sealed room/building provide ventilation

energy efficiency? Provide some energy statistics??

ENERGY/COMFORT

Case Study- Barrier Management

Total Barrier

Management

Infection control

Sound

Energy/ Movement

UL systems

Total Barrier Management practices increase build integrity and infection prevention secondary attributes

Control of aerosol important principal for airborne

infectious agents causing tuberculosis or aspergillosis depends on airflow control. Aerosol management due to patient derived symptoms needs masking and special room ventilation. Aerosol control is dependent on airflow direction intensity.

Excess room leakage will diminish pressure

management design. A sealed room will help provide consistent direction for prevention of occupational exposures to droplet nuclei containing Mycobacterium tuberculosis or chicken pox

INFECTION PREVENTION

Infection Prevention and Ventilation

• Air volumes must be maintained to assure cleaning the air of contaminants

• Impediments include: plugged equipment that needs cleaning or change out of filters

• Aspiring to have good air quality requires routine maintenance to assure AC/hr, filtration and pressure.